Can you help me decide what situation(s) a complete removal of packages is a wise and necessary step before an upgrade (current- , i386) ? .. someone -I recall- described such a step as an overkill .. so when is it nothing but an overkill ? and when is it an obligatory step to a clean and stabe system?

( In fact, -laught at it if you feel so- I never did an upgrade without first removing all packages , until yesterday : I upgraded and sysmerged then did a simple pkg_add -u .. it took some time .. it was all ok :-) .. )

pkg_delete runs in perl, your operating shell should not effect it. However, if this was the root user, and not your personal userid, please be advised that you should always leave root's shell as one of the built-in shells, and never use a third party shell for that account.

We're not going to be able to help you with your failed pkg_delete without an actual problem report -- please refer to the "perfect newbie" thread we've sent you to some half a dozen times or so.

You did not need to delete your packages. # pkg_add -iu was all that was needed to upgrade any installed packages with newer signatures residing at your $PKG_PATH.

jgimmi & ocicat, thank you very much !!
Ocicat , you said : none .. even in a case like when the packages are a few months old? maybe some packages would cease to exist or change names or something ..
Does it harm stability keeping older packages with an updated system? (eg. cases : when lacking enough time to update a mass of 16g packages .. or with some recurring network service problem .. etc)

OS libraries (/usr/lib) are not removed in upgrades, and remain forever.

Third party libraries (/usr/local/lib) will remain installed when they are in the dependency chain for an installed package. If there are newer versions of these libraries, the older libraries remain in the package database in /var/db/pkg/.libs* - so, you only need to delete older packages when you no longer need them.